1. Field of the Invention
This invention relates to a photothermal structure that is useful for the thermal ablation of tissue, such as for the creation of micropores.
2. Discussion of the Art
Traditional glucose monitoring devices operate on the principle of taking blood from an individual by a variety of methods, such as by needle or lancet. An individual applies a drop a blood to a strip which contains chemistry that interacts with the blood. The strip is inserted into a blood-glucose meter for measurement of glucose concentration based on a change in reflectance of the strip.
There are alternative glucose monitoring technologies being developed to provide a less invasive monitoring technique. One such technology involves measuring the level of glucose in interstitial fluid. In order to obtain samples of interstitial fluid, the barrier function of the stratum corneum must be overcome.
U.S. patent application Ser. No. 08/776,863 entitled xe2x80x9cMicroporation Of Human Skin For Drug Delivery and Monitoring Applications,xe2x80x9d filed Feb. 7, 1997, to Eppstein et al., discloses a method of ablating the stratum corneum to form at least one micropore by treating a selected area of the stratum corneum with an effective amount of an optical absorbing compound that exhibits strong absorption over the emission range of a light source and thermally ablating the stratum corneum by optically heating the optical absorbing compound. Heat is conductively transferred by the compound to the stratum corneum to elevate the temperature of tissue-bound water and other vaporizable substances in the selected area above the vaporization point of water and other vaporizable substances. This technique is hereinafter referred to as optical thermal ablation. Another microporation technique disclosed in that application involves the use of a solid thermal probe that is applied directly to the tissue. To the subject, these techniques are much less painful than using a lancet, if not completely painless.
In order to optimize the performance of the optical thermal ablation technique, it is desirable to accurately dispose a quantity of optical absorbing compound in contact with the tissue to be treated.
Briefly, the present invention is directed to a method and structure for the uniform application of a photothermal or photothermal material, such as, for example, a dye or a pigment, to a tissue, e.g., the stratum corneum, for the purpose of photothermal treatment of the tissue. In one embodiment, the photothermal structure comprises a photothermal material that is combined with a carrier, such as, for example, an adhesive or an ink, and the resulting combination is applied to a substrate, such as, for example, an inert polymeric substrate to form a photothermal structure. Means of application of the photothermal material to the carrier include, but are not limited to, printing, spraying, and casting. In another embodiment of a photothermal structure, the photothermal material may be incorporated into a film-forming polymeric material, and the resulting mixture can then be processed to form a film. The photothermal structure of either embodiment is placed in contact with the tissue, e.g., the stratum corneum, and illuminated with a light source, such as a laser.
The above and other objects and advantages of the present invention will become more readily apparent when reference is to made to the following description, taken in conjunction with the accompanying drawings.